output = "Hello, "

if #arg == 0 then
    output = output .. "World"
elseif #arg == 1 then  -- Initially forgot '.' in table access; no error
    output = output .. arg[1]
else
    for x=1, #arg-1 do
	output = output .. arg[x] .. ', '
    end
    output = output .. "and " .. arg[#arg]
end
print(output .. "!")
